Abstract In the second part of the review on electrochemical energy storage, the devolvement of batteries is explored. First, fundamental aspects of battery operation will be given, then, different materials and chemistry of rechargeable batteries will be explored, including each component of the cell. In negative electrodes, metallic, intercalation and transformation materials will be addressed. Examples are Li or Na metal batteries, graphite and other carbonaceous materials (such as graphene) for intercalation of metal-ions and transition metal oxides and silicon for transformation. In the positive electrode section, materials for intercalation and transformation will be reviewed. The state-of-the-art on intercalation as lithium cobalt oxide and nickel containing oxides will be approached for intercalation materials, whereas sulfur and metal-air will also be explored for transformation. Alongside, the role of electrolyte will be discussed concerning performance and safety, with examples for the next generation devices. Finally, a general future perspective will address both electrochemical capacitors and batteries.
Abstract The Nobel Prize in Chemistry 2019 recognized the importance of Li-ion batteries and the revolution they allowed to happen during the past three decades. They are part of a broader class of electrochemical energy storage devices, which are employed where electrical energy is needed on demand and so, the electrochemical energy is converted into electrical energy as required by the application. This opens a variety of possibilities on the utilization of energy storage devices, beyond the well-known mobile applications, assisting on the decarbonization of energy production and distribution. In this series of reviews in two parts, two main types of energy storage devices will be explored: electrochemical capacitors (part I) and rechargeable batteries (part II). More specifically, we will discuss about the materials used in each type of device, their main role in the energy storage process, their advantages and drawbacks and, especially, strategies to improve their performance. In the present part, electrochemical capacitors will be addressed. Their fundamental difference to batteries is explained considering the process at the electrode/electrolyte surface and the impact in performance. Materials used in electrochemical capacitors, including double layer capacitors and pseudocapacitive materials will be reviewed, highlighting the importance of electrolytes. As an important part of these strategies, synthetic routes for the production of nanoparticles will also be approached (part I).
Abstract: Since its inception in 2007, the Colloidal Materials Group, one of the research groups in nanotechnology of the Institute of Chemistry of São Carlos (IQSC) at University of São Paulo (USP) carries out studies related to the development of syntheses methods of nanoparticles and multifunctional nanostructured systems. Our works search new synthesis methodologies that allow high size and shape control of the individual nanoparticles or that compose the nanostructured systems and has as a principle the synthetic approaches based on the modified polyol and thermal decomposition processes. Systems involving nanoparticles have received extensive attention both in the fundamental research and in several technological applications exploring the unique properties presented in nanomaterials. These properties are strongly size- and shape-dependent of the nanoparticles and a large distribution of size or shape implies in a high response dispersion, justifying the intense research for the so-called nanoparticle monodisperse systems. In this review, we present the main aspects to obtain monodisperse nanoparticulate systems, correlating with the synthesis processes used in our group and some of our results in systems involving nanoparticles with magnetic, optical, and electronic properties, as well as some obtained composite materials for different applications.